[meta.trans.arr]

Table 60 — Array modifications [tab:meta.trans.arr]

🔗 Template	Comments
🔗 template<class T> struct remove_extent;	If T is a type “array of U”, the member typedef type denotes U, otherwise T. [Note 1: For multidimensional arrays, only the first array dimension is removed. For a type “array of const U”, the resulting type is const U. — end note]
🔗 template<class T> struct remove_all_extents;	If T is “multidimensional array of U”, the resulting member typedef type denotes U, otherwise T.

[Example 1: / the following assertions hold: static_assert(is_same_v<remove_extent_t<int>, int>); static_assert(is_same_v<remove_extent_t<int[2]>, int>); static_assert(is_same_v<remove_extent_t<int[2][3]>, int[3]>); static_assert(is_same_v<remove_extent_t<int[][3]>, int[3]>); — end example]

[Example 2: / the following assertions hold: static_assert(is_same_v<remove_all_extents_t<int>, int>); static_assert(is_same_v<remove_all_extents_t<int[2]>, int>); static_assert(is_same_v<remove_all_extents_t<int[2][3]>, int>); static_assert(is_same_v<remove_all_extents_t<int[][3]>, int>); — end example]